1. Technical Field
Example embodiments of the present invention relate to a technology of converting energy, and more specifically to an energy conversion apparatus which can achieve high conversion efficiency with a simple configuration.
2. Related Art
A technology of energy harvesting is a technology for harvesting circumjacent energy thrown away, converting it to usable energy, and storing the usable energy for later use. The technology may enhance energy performance of electric devices and the like, and make it possible to drive electric devices by using circumjacent energy without any additional energy supplied.
As examples of energy harvesting technologies, there are a sunlight generation using sunlight, a thermoelectric generation using Zeeback effect according to differences of temperature, a Piezoelectric generation for obtaining electric energy from kinetic energy such as circumjacent vibration or shock, and a technology of converting motions of human body into electric energy.
An apparatus for energy harvesting may comprise an energy harvester harvesting circumjacent energy and an energy converter converting the energy provided from the energy harvester into electric energy having a consistent level.
Here, in the energy harvester, amount of energy to be generated and impedance condition may be varied persistently according to its operating condition. Therefore, the energy converter should perform impedance matching to the energy harvester to maximize energy delivered from the energy harvester, which is called a Maximum Power Point Tracking (MPPT).
For this, the conventional energy converter comprises two direct current to direct current (DC-to-DC) converters for impedance matching and output voltage stabilization. The first DC-to-DC converted is used for matching impedance to that of the energy harvester, and the second DC-to-DC converter is used for stabilizing output voltage.
As described above, since the conventional energy converter uses two DC-to-DC converters, there is a problem that a constitution of circuit for implementing the energy converter should be complicated and the size of the energy harvesting apparatus should increase. Also, since two DC-to-DC conversions are performed in a procedure of energy conversion, energy losses can be occurred two times so that there is a limit to enhance energy conversion efficiency.